I apologize for being new here and posting about an issue many probably feel has been covered. I've lurked for a while and haven't found my symptoms addressed, so here I go.

My 1998 TJ Sport's engine started shaking funny last week. Sure enough, after a couple minutes the Check Engine light showed up. I parked it, and right when I put it in park the RPM's shot over 2k and stayed there. Checked the OBDII and it was P0123 (Throttle Position Sensor).

So, when the engine stopped shaking after turning the Jeep off, I turned it back on after replacing the TPS, and now the RPM's stayed at 2K when idle, and constantly cut-out while driving (for a split second or a couple it would just drift not reading that my foot was on the gas, and when it finally did it would jolt). I replaced the TPS with three different brands, same issues. I cleaned the original TPS, and when I put it back in the Jeep idled normally. Now one week has passed. I cleaned it again and I did a full system reset (did this each time I replaced it) and it does frequent cut-outs as I drove it about 15 miles. The 15 miles back home later it drove completely fine, no issues at all. Shocked, I drove it another 10, still no issues. Check engine light is still on.

I had this looked at by a master tech and he says he thinks the computer is bad and needs to be replaced. If anybody here has had something like this happen to them, I'd love to hear your story. Solutions always welcome as well.
Thanks a lot!
-Fellow Jeeper

That a so-called "Master tech" would immediately jump to the recommendation you need to buy a new computer is pretty shocking. I am betting he works for a dealer.

As Atthehop says, go first for a TPS purchased from the dealer...ask for a discount, they will likely give one to you. The sensors sold by the auto parts stores are usually junk imported from China that are hit-or-miss on their quality and reliability.

That a so-called "Master tech" would immediately jump to the recommendation you need to buy a new computer is pretty shocking. I am betting he works for a dealer.

As Atthehop says, go first for a TPS purchased from the dealer...ask for a discount, they will likely give one to you. The sensors sold by the auto parts stores are usually junk imported from China that are hit-or-miss on their quality and reliability.

Quote:

Originally Posted by Atthehop

Buy a TPS from the Dealer, they are the most reliable. Many have had problems with TPS's from auto parts stores.

I really appreciate the feedback, guys! I've read this on the Forum as well, and I took the advice, but no such luck. The dealer charged $108!
I was going to buy the one on the Quadratec website, but I thought (why try a fourth)
No, the "Master Tech" worked at a reputable repair shop nearby. He didn't jump to this conclusion immediately, he took almost two and a half hours. He did say in 20 years he has only replaced one TPS. But judging by this forum and all the TPS issues, he must have only worked on one Wrangler in the past 20 years :P
I drove the Jeep on the highway today with no issues still. I am floored by how the issues are suddenly gone after one week of brutality. Check Engine light is still on though.

I tried like heck to get mine off of the Throttle Body, but it has a stripped screw. I got a special drill bit set to help remove it, but it didn't work. Next, I tried slicing a line into it to remove it with a flat-head screwdriver, but even that didn't work.

An update. It has been running fine until a little while ago I had someone clear the check engine code, and of course it came back on. However, this time the rpm's shot almost 2,400 and it drives at about 33mph without my foot on a pedal.

This is not meant to be a "solution", but it made me so happy that I need to share. My check engine light turned off while I was off-roading in the woods. Must have been the computer getting wet. Happy off-roading, people.

My problem didn't actually go away. After going the night without a check engine light and no problems, I woke up to a misty morning with my jeep covered in a layer of moisture. Sure enough, I started it (after it wouldn't catch for a few seconds) and the rpm's in idle were at about 2.3k
I drove it around and started it over and over, as the day went on it finally went to a normal idle speed. I drove it offroad and the check engine light turned off again, same place. So, could this be a cracked vacuum or something that expands during cool mornings and shrinks when it is warmed up? Any ideas?
Thank you guys, you're all very helpful!